1. Field of the Invention
This invention relates to improvements in advanced BiCMOS processing methods and structures, and more particularly to improvements in methods for making programmable elements in advanced BiCMOS devices, and still more particularly to methods for making TiW fuses in a high performance BiCMOS process for field-programmable logic applications and to TiW fuses made thereby.
2. Relevant Background
Process techniques have been proposed for optimally merging advanced bipolar and advanced CMOS techniques to fabricate BiCMOS devices. Examples are shown in U.S. Pat. Nos. 4,962,053 and 5,065,208, assigned to the assignee hereof. However, these approaches in BiCMOS processing have been directed primarily towards non-programmable logic and SRAM applications. These applications do not require the formation of TiW fuses for programmation. The merger of bipolar and CMOS process flows for these applications is therefore the primary concern discussed in the two aforementioned patents.
For those circuits that require fuses for programming such as field programmable logic (FPL) circuits, there is a need to modify the process so that the fuses can be incorporated in the process with minimal changes to the basic process flow. The present invention discusses several methods for incorporating fuses, in general, and TiW fuses, in particular, with the minimal addition of processing to advanced BiCMOS processes proposed heretofore.